I ran a cryptic sponge tank for over 3 years. It took about a year to really grow in. Like my experience with a lit macro fuge, I never saw much of an advantage from a filtration perspective but I'm sure it helped since sponges are filter feeders. I did however find it beneficial from a food source perspective. I had the cryptic sponge tank gravity feeding my display and lots of little plankton would get sucked down into the display creating a constant food source for my fish and corals.
The system:
The tank was a 40 gallon breeder with black vinyl on the back and two ends, with a black front panel and black top. It had a 3' strip light for occasional viewing. There were 2 - 1" buklheads in the top corners of back panel. One for the feed, the other was a drain that gravity fed to my display.
Livestock:
There is about 55-60lbs of nice liverock. Some creatures included feather dusters, many different sponge varieties, jelly fish, nudibranchs, copepods, amphipods, and large worms over 2-3' that makeup my nightmares. The nice thing about it is it required very little. An airstone, about 75-125 gph feed and that's it!
Check out "The Environmental Gradient- Cryptic Sponge and Sea Squirt Filtration Models" by Steve Tyree, to learn more about sponge filtration in the hobby.
I use photobucket and they just blocked usage on 3rd party sites like forums. Once I get an flickr account set up I will post photos.
